"∁" meaning in Translingual

{
  "head_templates": [
    {
      "args": {
        "1": "mul",
        "2": "symbol"
      },
      "expansion": "∁",
      "name": "head"
    }
  ],
  "lang": "Translingual",
  "lang_code": "mul",
  "pos": "symbol",
  "senses": [
    {
      "categories": [
        {
          "kind": "other",
          "name": "Translingual entries with incorrect language header",
          "parents": [
            "Entries with incorrect language header",
            "Entry maintenance"
          ],
          "source": "w"
        },
        {
          "kind": "topical",
          "langcode": "mul",
          "name": "Set theory",
          "orig": "mul:Set theory",
          "parents": [
            "Mathematics",
            "Formal sciences",
            "Sciences",
            "All topics",
            "Fundamental"
          ],
          "source": "w"
        }
      ],
      "examples": [
        {
          "text": "If a universe U is defined, then the complement of a set A is denoted by the following equivalent notations A^C, A′, ∁A, ∁_UA, or U ∖ A.",
          "type": "example"
        }
      ],
      "glosses": [
        "Complement (absolute)."
      ],
      "id": "en-∁-mul-symbol-i~UKCV3~",
      "links": [
        [
          "set theory",
          "set theory"
        ],
        [
          "Complement",
          "complement"
        ]
      ],
      "raw_glosses": [
        "(set theory) Complement (absolute)."
      ],
      "related": [
        {
          "word": "∖"
        }
      ],
      "topics": [
        "mathematics",
        "sciences",
        "set-theory"
      ]
    }
  ],
  "word": "∁"
}

{
  "head_templates": [
    {
      "args": {
        "1": "mul",
        "2": "symbol"
      },
      "expansion": "∁",
      "name": "head"
    }
  ],
  "lang": "Translingual",
  "lang_code": "mul",
  "pos": "symbol",
  "related": [
    {
      "word": "∖"
    }
  ],
  "senses": [
    {
      "categories": [
        "Translingual entries with incorrect language header",
        "Translingual lemmas",
        "Translingual symbols",
        "Translingual terms with usage examples",
        "mul:Set theory"
      ],
      "examples": [
        {
          "text": "If a universe U is defined, then the complement of a set A is denoted by the following equivalent notations A^C, A′, ∁A, ∁_UA, or U ∖ A.",
          "type": "example"
        }
      ],
      "glosses": [
        "Complement (absolute)."
      ],
      "links": [
        [
          "set theory",
          "set theory"
        ],
        [
          "Complement",
          "complement"
        ]
      ],
      "raw_glosses": [
        "(set theory) Complement (absolute)."
      ],
      "topics": [
        "mathematics",
        "sciences",
        "set-theory"
      ]
    }
  ],
  "word": "∁"
}